1 /*
2  * Copyright (C) 2010 Alex Milowski (alex@milowski.com). All rights reserved.
3  * Copyright (C) 2010 François Sausset (sausset@gmail.com). All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
15  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
16  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
17  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
18  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
19  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
20  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include "config.h"
28 
29 #if ENABLE(MATHML)
30 
31 #include "RenderMathMLOperator.h"
32 
33 #include "FontSelector.h"
34 #include "MathMLNames.h"
35 #include "RenderText.h"
36 
37 namespace WebCore {
38 
39 using namespace MathMLNames;
40 
RenderMathMLOperator(Node * container)41 RenderMathMLOperator::RenderMathMLOperator(Node* container)
42     : RenderMathMLBlock(container)
43     , m_stretchHeight(0)
44     , m_operator(0)
45 {
46 }
47 
RenderMathMLOperator(Node * container,UChar operatorChar)48 RenderMathMLOperator::RenderMathMLOperator(Node* container, UChar operatorChar)
49     : RenderMathMLBlock(container)
50     , m_stretchHeight(0)
51     , m_operator(convertHyphenMinusToMinusSign(operatorChar))
52 {
53 }
54 
isChildAllowed(RenderObject *,RenderStyle *) const55 bool RenderMathMLOperator::isChildAllowed(RenderObject*, RenderStyle*) const
56 {
57     return false;
58 }
59 
60 static const float gOperatorSpacer = 0.1f;
61 static const float gOperatorExpansion = 1.2f;
62 
stretchToHeight(int height)63 void RenderMathMLOperator::stretchToHeight(int height)
64 {
65     if (height == m_stretchHeight)
66         return;
67     m_stretchHeight = static_cast<int>(height * gOperatorExpansion);
68 
69     updateBoxModelInfoFromStyle();
70     setNeedsLayout(true);
71 }
72 
layout()73 void RenderMathMLOperator::layout()
74 {
75     // FIXME: This probably shouldn't be called here but when the operator
76     // isn't stretched (e.g. outside of a mrow), it needs to be called somehow
77     updateFromElement();
78     RenderBlock::layout();
79 }
80 
81 // This is a table of stretchy characters.
82 // FIXME: Should this be read from the unicode characteristics somehow?
83 // table:  stretchy operator, top char, extension char, bottom char, middle char
84 static struct StretchyCharacter {
85     UChar character;
86     UChar topGlyph;
87     UChar extensionGlyph;
88     UChar bottomGlyph;
89     UChar middleGlyph;
90 } stretchyCharacters[13] = {
91     { 0x28  , 0x239b, 0x239c, 0x239d, 0x0    }, // left parenthesis
92     { 0x29  , 0x239e, 0x239f, 0x23a0, 0x0    }, // right parenthesis
93     { 0x5b  , 0x23a1, 0x23a2, 0x23a3, 0x0    }, // left square bracket
94     { 0x2308, 0x23a1, 0x23a2, 0x23a2, 0x0    }, // left ceiling
95     { 0x230a, 0x23a2, 0x23a2, 0x23a3, 0x0    }, // left floor
96     { 0x5d  , 0x23a4, 0x23a5, 0x23a6, 0x0    }, // right square bracket
97     { 0x2309, 0x23a4, 0x23a5, 0x23a5, 0x0    }, // right ceiling
98     { 0x230b, 0x23a5, 0x23a5, 0x23a6, 0x0    }, // right floor
99     { 0x7b  , 0x23a7, 0x23aa, 0x23a9, 0x23a8 }, // left curly bracket
100     { 0x7c  , 0x23d0, 0x23d0, 0x23d0, 0x0    }, // vertical bar
101     { 0x2016, 0x2016, 0x2016, 0x2016, 0x0    }, // double vertical line
102     { 0x7d  , 0x23ab, 0x23aa, 0x23ad, 0x23ac }, // right curly bracket
103     { 0x222b, 0x2320, 0x23ae, 0x2321, 0x0    } // integral sign
104 };
105 
106 // We stack glyphs using a 14px height with a displayed glyph height
107 // of 10px.  The line height is set to less than the 14px so that there
108 // are no blank spaces between the stacked glyphs.
109 //
110 // Certain glyphs (e.g. middle and bottom) need to be adjusted upwards
111 // in the stack so that there isn't a gap.
112 //
113 // All of these settings are represented in the constants below.
114 
115 // FIXME: use fractions of style()->fontSize() for proper zooming/resizing.
116 static const int gGlyphFontSize = 14;
117 static const int gGlyphLineHeight = 11;
118 static const int gMinimumStretchHeight = 24;
119 static const int gGlyphHeight = 10;
120 static const int gTopGlyphTopAdjust = 1;
121 static const int gMiddleGlyphTopAdjust = -1;
122 static const int gBottomGlyphTopAdjust = -3;
123 static const float gMinimumRatioForStretch = 0.10f;
124 
updateFromElement()125 void RenderMathMLOperator::updateFromElement()
126 {
127     // Destroy our current children
128     children()->destroyLeftoverChildren();
129 
130     // Since we share a node with our children, destroying our children will set our node's
131     // renderer to 0, so we need to re-set it back to this.
132     node()->setRenderer(this);
133 
134     // If the operator is fixed, it will be contained in m_operator
135     UChar firstChar = m_operator;
136 
137     // This boolean indicates whether stretching is disabled via the markup.
138     bool stretchDisabled = false;
139 
140     // We made need the element later if we can't stretch.
141     if (node()->nodeType() == Node::ELEMENT_NODE) {
142         if (Element* mo = static_cast<Element*>(node())) {
143             AtomicString stretchyAttr = mo->getAttribute(MathMLNames::stretchyAttr);
144             stretchDisabled = equalIgnoringCase(stretchyAttr, "false");
145 
146             // If stretching isn't disabled, get the character from the text content.
147             if (!stretchDisabled && !firstChar) {
148                 String opText = mo->textContent();
149                 for (unsigned int i = 0; !firstChar && i < opText.length(); i++) {
150                     if (!isSpaceOrNewline(opText[i]))
151                         firstChar = opText[i];
152                 }
153             }
154         }
155     }
156 
157     // The 'index' holds the stretchable character's glyph information
158     int index = -1;
159 
160     // isStretchy indicates whether the character is streatchable via a number of factors.
161     bool isStretchy = false;
162 
163     // Check for a stretchable character.
164     if (!stretchDisabled && firstChar) {
165         const int maxIndex = WTF_ARRAY_LENGTH(stretchyCharacters);
166         for (index++; index < maxIndex; index++) {
167             if (stretchyCharacters[index].character == firstChar) {
168                 isStretchy = true;
169                 break;
170             }
171         }
172     }
173 
174     // We only stretch character if the stretch height is larger than a minimum size (e.g. 24px).
175     bool shouldStretch = isStretchy && m_stretchHeight>gMinimumStretchHeight;
176 
177     // Either stretch is disabled or we don't have a stretchable character over the minimum height
178     if (stretchDisabled || !shouldStretch) {
179         m_isStacked = false;
180         RenderBlock* container = new (renderArena()) RenderMathMLBlock(node());
181 
182         RefPtr<RenderStyle> newStyle = RenderStyle::create();
183         newStyle->inheritFrom(style());
184         newStyle->setDisplay(INLINE_BLOCK);
185         newStyle->setVerticalAlign(BASELINE);
186 
187         // Check for a stretchable character that is under the minimum height and use the
188         // font size to adjust the glyph size.
189         int currentFontSize = style()->fontSize();
190         if (!stretchDisabled && isStretchy && m_stretchHeight > 0 && m_stretchHeight <= gMinimumStretchHeight  && m_stretchHeight > currentFontSize) {
191             FontDescription desc;
192             desc.setIsAbsoluteSize(true);
193             desc.setSpecifiedSize(m_stretchHeight);
194             desc.setComputedSize(m_stretchHeight);
195             newStyle->setFontDescription(desc);
196             newStyle->font().update(newStyle->font().fontSelector());
197         }
198 
199         container->setStyle(newStyle.release());
200         addChild(container);
201 
202         // Build the text of the operator.
203         RenderText* text = 0;
204         if (m_operator)
205             text = new (renderArena()) RenderText(node(), StringImpl::create(&m_operator, 1));
206         else if (node()->nodeType() == Node::ELEMENT_NODE)
207             if (Element* mo = static_cast<Element*>(node()))
208                 text = new (renderArena()) RenderText(node(), mo->textContent().replace(hyphenMinus, minusSign).impl());
209         // If we can't figure out the text, leave it blank.
210         if (text) {
211             RefPtr<RenderStyle> textStyle = RenderStyle::create();
212             textStyle->inheritFrom(container->style());
213             text->setStyle(textStyle.release());
214             container->addChild(text);
215         }
216     } else {
217         // Build stretchable characters as a stack of glyphs.
218         m_isStacked = true;
219 
220         if (stretchyCharacters[index].middleGlyph) {
221             // We have a middle glyph (e.g. a curly bracket) that requires special processing.
222             int half = (m_stretchHeight - gGlyphHeight) / 2;
223             if (half <= gGlyphHeight) {
224                 // We only have enough space for a single middle glyph.
225                 createGlyph(stretchyCharacters[index].topGlyph, half, gTopGlyphTopAdjust);
226                 createGlyph(stretchyCharacters[index].middleGlyph, gGlyphHeight, gMiddleGlyphTopAdjust);
227                 createGlyph(stretchyCharacters[index].bottomGlyph, 0, gBottomGlyphTopAdjust);
228             } else {
229                 // We have to extend both the top and bottom to the middle.
230                 createGlyph(stretchyCharacters[index].topGlyph, gGlyphHeight, gTopGlyphTopAdjust);
231                 int remaining = half - gGlyphHeight;
232                 while (remaining > 0) {
233                     if (remaining < gGlyphHeight) {
234                         createGlyph(stretchyCharacters[index].extensionGlyph, remaining);
235                         remaining = 0;
236                     } else {
237                         createGlyph(stretchyCharacters[index].extensionGlyph, gGlyphHeight);
238                         remaining -= gGlyphHeight;
239                     }
240                 }
241 
242                 // The middle glyph in the stack.
243                 createGlyph(stretchyCharacters[index].middleGlyph, gGlyphHeight, gMiddleGlyphTopAdjust);
244 
245                 // The remaining is the top half minus the middle glyph height.
246                 remaining = half - gGlyphHeight;
247                 // We need to make sure we have the full height in case the height is odd.
248                 if (m_stretchHeight % 2 == 1)
249                     remaining++;
250 
251                 // Extend to the bottom glyph.
252                 while (remaining > 0) {
253                     if (remaining < gGlyphHeight) {
254                         createGlyph(stretchyCharacters[index].extensionGlyph, remaining);
255                         remaining = 0;
256                     } else {
257                         createGlyph(stretchyCharacters[index].extensionGlyph, gGlyphHeight);
258                         remaining -= gGlyphHeight;
259                     }
260                 }
261 
262                 // The bottom glyph in the stack.
263                 createGlyph(stretchyCharacters[index].bottomGlyph, 0, gBottomGlyphTopAdjust);
264             }
265         } else {
266             // We do not have a middle glyph and so we just extend from the top to the bottom glyph.
267             int remaining = m_stretchHeight - 2 * gGlyphHeight;
268             createGlyph(stretchyCharacters[index].topGlyph, gGlyphHeight, gTopGlyphTopAdjust);
269             while (remaining > 0) {
270                 if (remaining < gGlyphHeight) {
271                     createGlyph(stretchyCharacters[index].extensionGlyph, remaining);
272                     remaining = 0;
273                 } else {
274                     createGlyph(stretchyCharacters[index].extensionGlyph, gGlyphHeight);
275                     remaining -= gGlyphHeight;
276                 }
277             }
278             createGlyph(stretchyCharacters[index].bottomGlyph, 0, gBottomGlyphTopAdjust);
279         }
280     }
281 }
282 
createStackableStyle(int size,int topRelative)283 RefPtr<RenderStyle> RenderMathMLOperator::createStackableStyle(int size, int topRelative)
284 {
285     RefPtr<RenderStyle> newStyle = RenderStyle::create();
286     newStyle->inheritFrom(style());
287     newStyle->setDisplay(BLOCK);
288 
289     FontDescription desc;
290     desc.setIsAbsoluteSize(true);
291     desc.setSpecifiedSize(gGlyphFontSize);
292     desc.setComputedSize(gGlyphFontSize);
293     newStyle->setFontDescription(desc);
294     newStyle->font().update(newStyle->font().fontSelector());
295     newStyle->setLineHeight(Length(gGlyphLineHeight, Fixed));
296     newStyle->setVerticalAlign(TOP);
297 
298     if (size > 0)
299         newStyle->setMaxHeight(Length(size, Fixed));
300 
301     newStyle->setOverflowY(OHIDDEN);
302     newStyle->setOverflowX(OHIDDEN);
303     if (topRelative) {
304         newStyle->setTop(Length(topRelative, Fixed));
305         newStyle->setPosition(RelativePosition);
306     }
307 
308     return newStyle;
309 }
310 
createGlyph(UChar glyph,int size,int charRelative,int topRelative)311 RenderBlock* RenderMathMLOperator::createGlyph(UChar glyph, int size, int charRelative, int topRelative)
312 {
313     RenderBlock* container = new (renderArena()) RenderMathMLBlock(node());
314     container->setStyle(createStackableStyle(size, topRelative).release());
315     addChild(container);
316     RenderBlock* parent = container;
317     if (charRelative) {
318         RenderBlock* charBlock = new (renderArena()) RenderBlock(node());
319         RefPtr<RenderStyle> charStyle = RenderStyle::create();
320         charStyle->inheritFrom(container->style());
321         charStyle->setDisplay(INLINE_BLOCK);
322         charStyle->setTop(Length(charRelative, Fixed));
323         charStyle->setPosition(RelativePosition);
324         charBlock->setStyle(charStyle);
325         parent->addChild(charBlock);
326         parent = charBlock;
327     }
328 
329     RenderText* text = new (renderArena()) RenderText(node(), StringImpl::create(&glyph, 1));
330     text->setStyle(container->style());
331     parent->addChild(text);
332     return container;
333 }
334 
baselinePosition(FontBaseline,bool firstLine,LineDirectionMode lineDirection,LinePositionMode linePositionMode) const335 int RenderMathMLOperator::baselinePosition(FontBaseline, bool firstLine, LineDirectionMode lineDirection, LinePositionMode linePositionMode) const
336 {
337     if (m_isStacked)
338         return m_stretchHeight * 2 / 3 - (m_stretchHeight - static_cast<int>(m_stretchHeight / gOperatorExpansion)) / 2;
339     return RenderBlock::baselinePosition(AlphabeticBaseline, firstLine, lineDirection, linePositionMode);
340 }
341 
342 }
343 
344 #endif
345